Container for controlling dry ice



Sept. 28, 1937. .c. H. WALKER CONTAINER FOR CONTROLLING DRY ICE Filed Feb. 25, 1935 FIG..

null/L744 A Ill INVENTOR:

CLARENCE H.WALK R 5Y3 E ATTORNEY Patented Sept. 28, 1937 UNITED- STATES.

PATENT OFFICE 2,094,389 CONTAINER Foa con'monnme DRY 1cm Clarence H. Walker, San Mateo, Calif. Application February 25, 1935-, sci-m1 No. 7,996 1 Claim. (01. 62-91.5)

' the deleterious effects of CO: gas.

Other objects andadvantages will appear as the description progresses.

In this specification and the accompanying drawing the invention is disclosed in its preferred form. It is to be understood, however, that it is not limited to this particular form because it may be embodied in other forms within the purview of the claim following the description.

v In the description and claim the trade name dry ice will be used to define CO2 in solid form and/or any chemical or other product that will give a similar refrigerating effect when evaporated or vaporized in a container having a callbrated or controlled outlet for the products of evaporation.

The carbonic acid gases forming part of the Vapors of evaporation of CO2 are deleteriousto certain products, notably cut flowers in shipping boxes. It is also very important that temperature regulation be accurately controlled to prevent a drop in temperature with the danger of freezing or a rise to a degree where the flowers will wilt because of the loss of moisture.

The following description will be devoted more particularly to the use of" the invention in connection with the shipment of out fiowers.- It will be recognized that the general conditions of this adaptation apply equally to the preservation oi. other perishables aifected by variations in temperature and deleterious by-products of refrigeration.

' In the one sheet of drawings:

Fig. 1 is a side elevation of a shipping package, partially in vertical section showing this invention combined therewith.

Fig. 2 is a fragmentary enlarged detail of the dry ice container having an evaporation control outlet, in accordance with this invention. Fig. 3 is a similar view of a modification of the same.

Fig. 4 is a fragmentary portion of a container.

in vertical section showing a needle valve for manually adjusting. the gas flow.

Fig. 5 is a plan view of a scroll thermostat applicable to thevalve shown in Fig. 4 for thermostatically controlling the gas flow.

In detail the construction illustrated in the drawing referring first to Fig. 1. comprises the container 1, such as a conventional tin can", having the friction cover 2 and adapted to contain the dry ice 3'. It is intended that the cover 2 hermetically seal the contents within the container l. The friction type of. cover 2 has the further advantage that it will relieve or blow out should an excess pressure be generated within the container.

The vent pipe 4 is fixed in the cover 2 and provides an'escape for the gases of evaporation, from the container, see Fig. 2. By pinching the end of the pipe 4 a restricted orifice is formed at 5. This orifice can be calibrated and proportioned to the quantity of dry ice 8 in the container, and the temperature desired over a given period of time.

In the shipment of perlshables, such as flowers for relatively short distances the quantity of dry ice may be comparatively small with respect to the cubic capacity of the shipping box. To prevent over refrigeration the orifice 5 must be very small to prevent a too rapid evaporation with. a consequent drop in temperature.

Further protection can be assured by the interliner 6 of insulating material such as cell board or the like interposed between the dry ice and the walls of the container. This reduces the heat exchange between the dry ice and the atmosphere, by confining the exchange largely to the metal ends 2 and i. These ends gradually absorb heat from the air impounded in the box 8 andaccumulate frost. This frost acting as an insulator retards evaporation of the dry ice 3. Contrawise if the temperature in the box 8 rises, the frost is dissipated and speeds up evaporation of the dry ice. and restores the temperature as determined by the calibrated orifice 5. The back pressure created by this restricted orifice 5 as it builds up retards evaporation of the dry ice within the container 8. Obviously the greater area of heat exchange free surface on the container,

reducing the heat exchange area, as by the insulation 6, refrigeration can be accurately controlled with respect to surrounding conditions.

Where the CO2 products given off by the evap- A I oration of the dry ice are deleterious to the contents of the box 8, they can be vented through the wall of the boxand discharged into the atmosphere, see Fig. 1.

It is important that there be nocirculation between the inside air in the box 8,-and the atmosphere surrounding it, which would interfere with maintaining the proper-temperature within the box 8. This is very eifectively and cheaply accomplished by forming an inturned flange 9 surrounding the top of the box, the edge of which bears against the inner plane in of the cover ll of the box. The outer flange i2 of the cover completes the sealing of the box against air leakage when the cover is tied to the box by encircling twine or otherwise. The greatest danger to the contents of the box 8 is a sudden rise in temperature within the box when taken from storage, as in unloading carriers, exposure to sunshine and the like. This danger is practically eliminated if the box 8 is reasonably air tight, to prevent the loss of impounded refrigerated air faster than the dry ice unit I can function. The box and cover are preferably composed of the conventional corrugated or cell board which has a high thermo-insulating value in proportion to weight. The optimum thickness'of insulation for any particular case is found by balancing the cost of construction against the cost of refrigeration.

The particular structure of the shipping box forms the subject matter of my copending application filed November 19, -l934,-'under Serial #753,711, and entitled Boxes, to which the present invention is adapted for portable packages.

A modified form of vent is shown in Fig. 3 in which a thin diaphragm I3 is fixed to the cover 2w by the hollow rivet I4. A needle can be used to puncture this diaphragm at 52:, asmany punctures of known capacity being formed to meet the desired conditions of refrigeration.

Where large cubic capacity of refrigeration demands increased quantities of dry ice, larger containers may be used and multiplied for location.

at proper points throughout the area to be refrigerated.

Tomeet known conditions a container having metal ends and-a body composed of card board such as Ix, Fig. 2, may be used to avoid the necessity of insulating the inner or outer wall of the container as in Fig. 1.

As in Fig. 1 the container can be strapped to the underside of the cover II with the gummed tape l5 and the vent pipe 4 carried through the box at any desired point.

In Fig. 4, the cover 2 may be provided with the valve body l6 fixed therein and provided with the side outlet l'I, adapted to receive a tube to vent the escaping CO2 outside the refrigerated area. 1

The needle valve l8 cooperating with the valve seat at I9, is threaded at in the body Hi. The squared head 2| receives the disc handle 22. The periphery of this handle frictionally engages the stud 23 on the slightly yielding bracket 24 extending outward from the body I6. This frictional contact is adapted to hold the valve in adjusted position.

In Fig. 5, 'a bimetallic thermocouple scroll 25 forms a conventional thermostat attached at its axis to the squared head 2| of the valve and has its outer end looped around the stud 23. The expansion and contraction of the thermostatic scroll under temperature variations rotates the valve to vary the volume 'of gas liberated from .the container.

Heretofore it has been the practice to retard the gasification of dry ice by increasing its' density by mechanical compression; and by thermoinsulation. So far as known to applicant it is new to control refrigeration by regulating the evaporation of dry ice by restricting the escape of CO2 and causing a rise of gas pressure within the dry ice container. 1 Having thus described this invention, what is claimed and desired to secure by Letters Patent 1s:

A shipping package including a box having a. substantially tight cover; a container for dry ice (solid CO2) having a gas tight friction closure; and a bendable vent pipe having one end fixed in said closure and terminating outside said box.

- CLARENCE H. WALKER. 

